The present research concerns the use of in vitro toxicity testing methods for studying the cytotoxic effects of metal compounds induced in four different cell lines such as HaCaT, PC12, ES D3 and BALB/3T3 as models of dermal toxicity, neurotoxicity, embryotoxicity and carcinogenic potential of xenobiotics. The following studies have been carried out:- HaCaTa) Determination of cytoxicity of Pt compounds ((NH4)2PtCl4, (NH4)2PtCl6, PtCl2 and PtCl4) as measured by Colony Forming Efficiency (CFE). PtCl2 and (NH4)2PtCl6 were more cytotoxic compared to PtCl4 and (NH4)2PtCl4. The cytotoxic responses of the four platimun species was dependent of the time of exposure and on the chemical form of the element.b) Screening test of the cytotoxic induced by 100 mM of 51 metal compounds at 72h post-exposure. This allowed a classification of the metal species tested as 3 groups according to the severity of the degree of their cytotoxic response.- PC12Screening test on the cytotoxic response in relation to the exposure to 100 mM of 24 metal compounds for 24h and 72h as determined by MMT test. The study has been carried out on cells that were grown in absence or presence of tetracycline, a technique that makes (Tet-on) or not (Tet-off) possible the expression p53 gene.Metal compounds which affect cell viability are Ag, As, Cd, Cr, Pt, Se and Te.- ES D3Effect of methyl mercury on the beating of ES cells, Cytotoxic effect of the metal compound was observed during the first step of differentiation.- BALB/3T3Inorganic and organoarsenic species have been studied for their cytotoxic and carcinogenic potential. Unlike NaAsO2 and Na2HAsO4 the organoarsenic forms arsenobetaine and arsenocholine failed to induce any significant cytotoxic effect in the cells, the inorganic As species (but not the organic ones) giving positive results in the morphological neoplastic transformation assay. These findings confirm that inorganic As compounds are biologically more active compared to organoarsenic species, and the great importance of the speciation as fundamental factor in determining the toxicological response.